Emma left home at 10.50 a.m. and drove towards the campsite. 3 hours later, her older brother left their home and drove towards the same campsite at 81 km/h. When the older brother reached the campsite at 6.50 p.m., Emma had another 3 km to travel. What was Emma’s average speed? Express your answer in mixed number.
Time that the Emma's older brother started driving = 1.50 p.m.
Duration that Emma's older brother drove from 1.50 p.m. to 6.50 p.m. = 5 h

Distance that Emma's older brother travelled
= 5 x 81
= 405 km

Distance that Emma travelled by the time her older brother reached the city
= 405 - 3
= 402 km

Time that Emma took to travel 402 km = 8 h

Emma's average speed
= 402 ÷ 8
= 50¹₄ km/h

Answer(s): 50¹₄ km/h